iio: lm3533: Use sysfs_emit()

iio: lm3533: Use sysfs_emit()

sysfs_emit() is preferred over raw s*printf() for sysfs attributes since it
knows about the sysfs buffer specifics and has some built-in checks for
size and alignment.

Use sysfs_emit() to format the custom device attributes of the lm3533
driver.  Note this driver was using scnprintf correctly so this change
is about ensuring examples of code that might get cut and paste into new
drivers are using current best practice.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20211216185217.1054495-8-lars@metafoo.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>